Rotary oxidizer systems for control of restaurant emissions

Abstract

A restaurant emissions abatement system is disclosed which employs a rotary heat regenerative thermal or catalytic oxidizer. Thus, heat which normally would be exhausted into the atmosphere, is recovered by being transferred to incoming unoxidized restaurant emissions. The rotary oxidizers may be of a variety of designs including orientations which allow for perpendicular or axial flow of the emissions stream through the rotary oxidizer relative to the axis of rotation. The rotary design of the oxidizers also provides an advantage of permitting in-situ cleaning of the oxidizer (i.e., not having to remove oxidizer from abatement system) by simply lowering the speed of the oxidizer's rotation or stopping rotation altogether to permit hot gases to thoroughly oxidize accumulations of such contaminants as greases and fats.

What is claimed is:  
     
       1. A system for removal of particulate matter and volatile organic compounds from a cooking emissions stream comprising: 
       an inlet duct for receiving a flow of the cooking emissions stream and directing the stream to a rotary, heat regenerative device having an axis of rotation such that the flow of the emissions stream through the rotary device is perpendicular or axial with reference to the axis of rotation of the rotary device;  
       the rotary device comprising:  
       (a) thermal oxidation and/or catalytic oxidation means whereby the emissions stream is thermally and/or catalytically oxidized;  
       (b) heat exchanger means to recover heat from the emissions stream after thermal and/or catalytic oxidation and before the oxidized emissions are returned to the atmosphere;  
       (c) one or more rotors, wherein a first rotor comprises a plurality of discrete heat exchange surfaces arranged in an axially parallel and longitudinal array, said first rotor having a first and second end, wherein the surfaces form a plurality of heat exchange channels;  
       (d) a transfer chamber connected to the second end of the first rotor;  
       (e) a sealing end plate adjoining the first end of the first rotor, wherein the end plate divides the first rotor into inlet and outlet compartments;  
       (f) an adjustable means for rotating the first rotor about the axis of rotation;  
       (g) a stationary or rotating second rotor, positioned between said first rotor and said transfer chamber, wherein said second rotor comprises a plurality of heat exchange surfaces arranged in an axially parallel and longitudinal array, said surfaces forming a plurality of heat exchange channels in fluid communication with said first rotor and said transfer chamber, said second rotor having a cell density greater than that of said first rotor and  
       an outlet duct for directing the oxidized emissions stream from the rotary device to the atmosphere.  
     
     
       2. The system of claim  1 , further comprising an exhaust fan in the outlet duct. 
     
     
       3. The system of claim  1 , further comprising a means for purging unreacted process gases from the first rotor. 
     
     
       4. The system of claim  1 , wherein the transfer chamber comprises a heat generating means for heating the emissions stream to a predetermined temperature. 
     
     
       5. The system of claim  1 , wherein the surfaces are catalytically coated. 
     
     
       6. The system of claim  4 , wherein the surfaces are catalytically coated. 
     
     
       7. The system of claim  1 , wherein the first rotor has a cell density of at least 25 cells per square inch. 
     
     
       8. The system of claim  7 , wherein the surfaces are formed in a honeycomb monolith comprising a metallic or ceramic substrate. 
     
     
       9. A system for removal of particulate matter and volatile organic compounds from a cooking emissions stream comprising: 
       a first heat exchange bed comprising a plurality of heat exchange surfaces, arranged in an axially parallel and longitudinal array, each of said surfaces having a first and a second end, wherein said surfaces form a plurality of heat exchange channels;  
       a transfer chamber communicating with the second end of said surfaces;  
       a second heat exchange bed, positioned between said first heat exchange bed and said transfer chamber, said second heat exchange bed comprising a plurality of heat exchange surfaces arranged in an axially parallel and longitudinal array, wherein said surfaces form a plurality of heat exchange channels in fluid communication with said first heat exchange bed and said transfer chamber, said second heat exchange bed having a cell density greater than that of said first heat exchange bed;  
       a sealing end plate adjoining the first end of said surfaces, wherein said end plate divides said channels into inlet and outlet zones;  
       a distribution plenum, fluidly communicating with said heat exchange surfaces;  
       a gas inlet plenum, fluidly communicating with said distribution plenum;  
       a gas outlet plenum, fluidly communicating with said gas distribution plenum; and  
       a one-piece, rotatable flow distributor, wherein said distributor fluidly communicates with said distribution, inlet and outlet plenums.